Last brew I calculated by brewhouse efficiency to be 63%. Not great, but I dialled this into BeerSmith and hoped my next brew would at least be predictable, even if I was not getting the most out of the grain.

I brewed a low ABV beer for my wife. BeerSmith calculated that I would hit 1.026, I managed 1.027

The issue I have is that when I post these numbers into http://www.brewersfriend.com/brewhouse-efficiency/ along with my grain bill, it calculates my efficiency as a whopping 73%!

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I don't understand how I can be so close to BeerSmiths predicted numbers, but so far above an the efficiency I have dialled into BeerSmith for my own gear!

  • I'd add that I had issues with downloading a beersmith recipe once because it changed my brewing equipment profile so those are factors you have to look at as well.
    – DHough
    Apr 18, 2016 at 21:50
  • in beer smith, is it calculating Brew house(BH) efficiency or brew kettle(BK) efficiency? when i put my number in for my brew day in brew target, I get 66.81% BK efficiency and 51.36 BH efficiency. This could be why you are getting different numbers.
    – jsolarski
    Apr 19, 2016 at 4:07
  • @jsolarski brewhouse
    – Mild Fuzz
    Apr 19, 2016 at 13:01
  • As far as the software/calculators question, are you saying you entered the same information and got different results, or you entered two different brews, one in beersmith and one in brewers friend and got different results?
    – Wyrmwood
    Apr 19, 2016 at 19:46
  • Beersmith correctly predicted my gravity based on a 63% efficiency. After brewing I looked to clarify my efficiency, but got a different value.
    – Mild Fuzz
    Apr 19, 2016 at 21:42

5 Answers 5


"... so far above an efficiency that BeerSmith is aware of"

I'm not exactly sure what you mean by this, I'm positive BeerSmith is aware of efficiencies above 73%.

It's very common to get higher efficiency on low-alcohol beers with smaller mashes since you're running proportionally more sparge water through each unit of volume of the mash bed, giving more opportunity for trapped extract to be leached out and recovered.

It's also not uncommon to see a fluctuation of ~5% efficiency between batches of the same beer, stemming from small differences in equipment setup and process. Do you have any other records of your efficiency or are these the first ones? It could just be the combination of a smaller mash coupled with a slightly more effective runoff.

  • I have rephrased to make my point a little more clear. I mean the efficiency BeerSmith has for my gear. How can the gravity prediction be correct but the two efficiency measurements be so far apart?
    – Mild Fuzz
    Apr 18, 2016 at 14:20
  • I think it's helpful to remember that one measurement of 63% efficiency doesn't mean your gear is locked at 63% efficiency, especially when varying batch size, strength, grain bill &c. You got 63% last time, 73% this time, and will probably find you get a different number next time (maybe every time). It's really best to track over a number of brews and see where it is on average (and also to watch how differences in your process or raw materials might manifest in different efficiencies). Apr 18, 2016 at 16:44
  • Agree 100%, and this is what I'm trying to do. My issue is just that I don't understand how Beersmith arrived at correct predictions even though the efficiency calculated was very different to the one dialled into the software.
    – Mild Fuzz
    Apr 18, 2016 at 17:39

I think that the issue is how both are calculated.

http://www.brewersfriend.com/brewhouse-efficiency/ is not accounting for losses in your equipment while beersmith is accounting for losses.

I think if you took out the losses in beersmith, you would get the same efficiency as brewersfriend.

  • ooh, that's interesting. One to watch out for.
    – Mild Fuzz
    Apr 20, 2016 at 8:05

I do BIAB and my efficiency has varied around 70% from 65% to 75%. I've found that something as simple as stirring my mash 3 times in the 60 minute rest and not stirring it can affect that number greatly. You're outside of the realms of common efficiencies in what you're doing. Certainly I know of people using Beersmith who have efficiencies into the 80's.

  • It's less a problem with the efficiency itself, more trying to understand why BeerSmith made the correct gravity prediction, but the efficiency measurements are totally out of whack. I am trying to decide if I can trust BeerSmith's predictions yet or if I have more configuration to to, and if so what I am missing.
    – Mild Fuzz
    Apr 18, 2016 at 14:22

Mash efficiency calculators are just an estimate based on an average yield on a specific grain.

They have a really wide range of results because they assume a perfect mash, with ideal crush, ph, water grain ratio, lauter technic etc. Once your brewhouse effeciency % is determined if those variables change your % will change.

To do it right they really need to factor mash thickness, ph, lauter details but I've not seen a calc tackle this yet.

More importantly grain harvests have different potentials* You need to update the potentials for each grain from the data sheet from your specific grain lots provided by the maltser. But this information is usually lost unless you buy by the bulk sack 50-55lb to get the lot # and look it up.

Mash ph plays such a big role in effeciency, your effeciency can be drastically different from batch to batch just from inconsistency in filtered tap water. Just one of the reasons to build water profiles from RO.


Gauging efficiency with 100% accuracy is not something you can really do from one brew to the next. You should certainly pay attention to it, and make small adjustments accordingly. Over time, you'll be able to accurately predict efficiency with your system for a specific recipe. Even then, there are some variables you don't have as much control over; water quality, ambient temperatures, humidity, etc. Even with the same recipe, sourced from the same ingredients, you can have some variance.

For example, I started assuming the standard 70% and for the most part, my brews were within acceptable differences, but because I keep meticulous records, I now know that I can reliably hit about 74% for most standard beers, ~70% for 50% wheat or very strong beers and 78% for session beers. I use kind of a goofy method to determine mash thickness, which plays a significant part, but I generally keep it between 1.5 and 2.0 qt/lb. When I create or modify a recipe for my system, I take that all that into account and can generally predict fairly closely the anticipated efficiency.

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